From my little knowledge of ict and computer technology I'd say yes they are cosed separately however most computer based websites are optimized for mobile phones as well so mobile phone users can get same feel of the websites just like the computer users.
That being said, not all websites are optimized for mobile phones some go extra mile to coded a separate website for mobile phond users. An example is the facebook website. Every facebook user would agree with me that when viewing the website through the phone on n. Facebook. Com, the interface, look and feel is quite different from when one is using a computer to visit www.facebook.com
This is because facebook coded the mobile website separately from the computer based website. But they both carry same information except that the computer based website has a lot of other options d mobile based website Can't carry